Thanks "h", that seems to confirm my rough reasoning that the use of a color filter array makes aliasing far worse. This is supported I suppose by the worse aliasing hat happens in video made from still sensors where only a selection of the photosites are read at all, so that it is closer to the "point samples" considered in the simplest mathematical models of sampling and aliasing.
So it would be nice if someone could produce an "X3" technology (all color information measured at each spatial location) which works better that the somewhat flawed, noise prone, Foveon implementation. Then the AA filter would be far less needed, or could at least have a lighter touch. I have read of patents on several alternative approaches to X3 from several major sensor makers, using stack of color filters and such, but at most these have been deployed in small, special purpose sensors.